1. Field of the Invention
The present invention relates to a radiation-sensitive resin composition containing an alkali-soluble resin, and more particularly to a radiation-sensitive resin composition which is sensitive to such radiations as ultraviolet rays, far ultraviolet rays, X-rays, electron beams, molecular beams, gamma-rays, synchrotron radiations, proton beams, etc. and suitable for use as a photoresist for fabrication of highly integrated circuits.
2. Description of the Prior Art
Positive type photoresists are widely used in the manufacture of integrated circuits, because they give photoresist patterns with high resolution. With the recent trend toward integrated circuits of higher integration, however, there has been a growing demand for a positive type photoresist from which a photoresist pattern with a further enhanced resolution can be formed. That is, in the formation of a fine photoresist pattern by use of a positive type photoresist, it is required that the development of a latent image, formed by exposure, with a developing solution consisting of an aqueous alkaline solution should proceed rapidly to the area where the exposed portion adjoin a wafer (namely, the base portion of the pattern).
However, the conventional positive type photoresists have a developability problem in that when the interval of pattern elements of the photoresist pattern to be formed is 0.8 .mu.m or below, an undeveloped residue called "scum" is liable to be left upon development.
In response to the increasing integration of integrated circuits, furthermore, the etching method for wafers has been changing from the conventional wet etching, which involves heavier side etching, to the dry etching with less side etching. In the dry etching, the photoresist pattern should not change during etching; therefore, the photoresist should have good heat resistance.